It's not like he has all that in money in his bank account, it's ownership of companies, their value is not real until someone else is willing to pay.
You have a vendetta against a guy, for grievances, some legitimate, and want the law to change, specifically to get him, because you hate what he says. You also want to nationalize his businesses, that he built, that he did not have to build, that now employ 140,000 people, that he did not have to employ, with those 140,000 people almost all being high income earners paying higher tax rates when they may not have otherwise, out of your hate.
I would call that greed and a despicable position.
On that note, it's also completely pointless. If you were to literally liquidate every billionaire in America, every single one, and somehow got current market rates for every single stock share, 100% tax rate beyond $1B... we would cover the deficit for 3 years. With everyone else still paying taxes. Then we're back to square one, running a $2T deficit every year with no billionaires to liquidate. It's entirely catharsis that accomplishes nothing. If such a tax were even passed, we wouldn't make it to the next election cycle before it's a problem again.
It would certainly impact their willingness to do the company-building that creates all those innovations and jobs.
With such a rule, Tesla wouldn't exist, no electric cars, no SpaceX, no cheap advanced launch tech; basically most of the modern world would be choked in the crib by taking away the incentive to build it.
Some people really are exceptional and there are very few of them.
How many Einsteins do you think are just kicking around? How many Robin Williams's or Tom Hanks's?
How many Kobes? We know not many because there's a huge search to find more.
There aren't 20 more Elons waiting in the wings there. Or 20 more Jensens. And so on.
It's actually far more rational as a society to pay the one guy who can create 100B his 10B for it.
And the last thing we need is 20 more Elons.
What it would impact is how easily these people could influence the political system and get themselves out of trouble.
At $400 billion net worth, Elon Musk could retire one hundred thousand times. He literally wrote multi-million dollar checks to various politicians and ran an illegal pay-for-votes scheme in Pennsylvania. And he'll face zero consequences for it.